Photoluminescence Sensor Research Articles

A highly stable 2D Zn-based coordination polymer exhibiting efficiently luminescent sensing towards sulfasalazine

A robust 3D supramolecular Zn(II)-based coordination polymer having formula [Zn(H2L)(bpyp)·H2O] (1) (H3L = benzene-1,3,5-tricarboxylic acid and bpyp = 2,5-bis(pyrid-4-yl)pyridine) has been hydrothermally synthesized and characterized. The single crystal X-ray analysis revealed that the polymer 1 possesses a paddle wheel-shaped [Zn2(COO)4] subunit extended by H3L and bpyp linkers, showing high environmental stability, good dispersion and intense green emission in aqueous system. 1 used as a photoluminescent sensor exhibits rapid and efficient fluorescent response towards sulfasalazine (SLA) with strong quenching constants and low detection limit of 1.65 ppm. Additionally, 1 exhibits strong anti-interference and outstanding regeneration capabilities in its sensitive and selective recognition of SLA, which enhances its potential for use as a sensing material. Furthermore, the sensing mechanism study shows that photo-induced charge transfer and competitive absorption are responsible for quenching of emission in 1.

A sensitive photoluminescent sensor based on highly charged monoruthenium(II) complexes for dopamine detection

A sensitive and selective photoluminescent sensor based on the highly charged monoruthenium(II) complex was designed to detect dopamine (DA) in aqueous samples. Two novel highly charged cationic ruthenium(II) complexes [Ru(bpy)2(bpy-N)]X4 (bpy = 2,2′-bipyridine, bpy-N = 4,4′-bis[N,N,N-triethyl-(methylamino)]-2,2′-bipyridine, X− = [PF6]− (1a) or Cl− (1b) and [Ru(bpy)(bpy-N)2]X6 (X− = [PF6]− (2a) or Cl−(2b)) can be assembled with anionic surfactant sodium dodecylbenzene sulfonate (SDBS), leading to an enhancement of photoluminescence intensity. Upon addition of DA to the system, the photoluminescence intensity of the assembled system was quenched due to the energy transfer effect. It exhibited a wide linear range (0.1–50 μM) and low detection limit (10 nM). The sensor demonstrated a high selectivity toward DA, especially in the presence of adrenaline (Adr) and norepinephrine (NE), whose structures are similar to DA in biological systems. With the merits of simple operation, obvious phenomenon and fast response speed, the sensor had a potential application prospect in human urine sample.

De novo design of a photoluminescent sensor for baicalin detection via regulating molecule-like charge transfer of gold nanocluster

Selective and sensitive detection of bioflavonoid glycosides remains a great challenge because the coexistence of their analogues in real samples will produce serious interference. Herein, baicalin was selected as an example to demonstrate that precise control of the molecule-like photoinduced charge transfer (PCT) behavior of gold nanoclusters (AuNCs) can be served as a new and efficient way to develop high-performance sensors for bioflavonoid glycosides detection. After a rational design was made using the prediction of a classical charge transfer theory, an AuNC-based photoluminescent sensor was constructed for baicalin determination. Such a sensor not only displayed high specificity toward baicalin in the presence of baicalein and other analogues of baicalin, but also could be applied in the analysis of baicalin content in the extract of Scutellaria baicalensis. Notably, the baicalin-involved PCT process was solidly revealed by steady and transient spectroscopic measurements for the first time. This study will inspire further work on sensors for the discrimination and screening of biomolecules from their analogues employing PCT techniques.

Folic Acid-Modified Cerium-Doped Carbon Dots as Photoluminescence Sensors for Cancer Cells Identification and Fe(III) Detection

Carbon dots (CDs) are a new class of carbon-based luminescence materials with fascinating properties. They have been given great expectations on superseding traditional semiconductor quantum dots due to their good dispersity and stability, relatively low toxicity, superior resistance to photobleaching, and excellent biocompatibility. The diversified luminescence properties of CDs are largely due to the synthetic strategies and precursors. In view of those described above, this study has explored the possibility to establish a facile one-step hydrothermal method for the one-pot synthesis of folic acid-modified cerium-doped CDs (Ce-CDs-FA), which could be further utilized as a sensitive fluorescent nanoprobe for biosensing. This investigation demonstrates that the Ce-CDs-FA nanocomposites have nice biocompatibility and bright fluorescent properties, which can be readily utilized to detect cancer cells through recognizing overexpressing folate receptors by virtue of folic acid. Meanwhile, it is noted that the Fe3+ ion can actualize a specific and hypersensitive quenching effect for these Ce-CDs-FA nanocomposites, which can be further explored for special ion recognition, including iron ions. It raises the possibility that the as-prepared Ce-CDs-FA nanocomposites could be extended as a dual fluorescence sensor for targeted cell imaging and Fe3+ ion detection.

Nitrogen-doped carbon quantum dots as a highly selective fluorescent and electrochemical sensor for tetracycline

Fluorescent nitrogen-doped carbon dots (N-CQDs) were fabricated from R. graveolens leaves following a green and facile hydrothermal process, yielding an 18 % quantum yield (QY). Multiple characterization techniques were used to conduct the optical, chemical, and morphological examination. The surface of the N-CQDs is abundant in hydroxyl, carbonyl, and amino groups, which provide excellent solubility, stability and sensing ability to the N-CQDs in the solution medium. The zeta potential analysis indicated that the N-CQD surface is negatively charged (−26.5 mV). It functions as a highly efficient and selective photoluminescent (PL) and an electrochemical sensor for tetracycline (TC). They exhibited excitation-dependent emission behaviour as a PL sensor with an excellent linear range from 0 to 600 nM and a LOD of 60 nM via the inner filter effect (IFE). Excellent sensitivity and selectivity towards TC with a linear range of 0–30 nM and LOD of 0.28 nM exhibited N-CQD as a highly selective electrochemical sensor. Fluorescent paper strips were also designed for the simple and rapid detection of TC present in both solid and solution states. Both developed sensors were effectively exploited to detect TC in real samples.

In situ-Synthesized cadmium sulfide quantum dots in pore-forming protein and polysaccharide matrices for optical biosensing applications

The main limitation for practical implementation of quantum dots-based sensors and biosensors is the possible contamination of sensing media with quantum dots (QDs) moved out from the sensor structure, being critical for living systems measurements. Numerous efforts have addressed the challenge of pre-synthesized QDs incorporation into porous matrix provide, on the one hand, proper fixation of quantum dots in its volume and preserving a free analyte transfer from the sensing media to them - on the other hand. Here, we propose an alternative insight into this problem. Instead of using preliminary synthesized particles for doping a matrix, we have in situ synthesized cadmium sulfide QDs in porous biopolymeric matrices, both in an aqueous solution and on a mica substrate. The proposed technique allows obtaining QDs in a matrix acting simultaneously as a ligand passivating surface defects and preventing QDs aggregation. The conjugates were used as a photoluminescence sensor for the metal ions and glutathione detection in an aqueous media. Different kinds of sensor responses have been found depending on the analyte nature. Zinc ions' presence initiates the intraband QDs emission increases due to the reduction of non-radiative processes. The presence of copper ions, in contrast, leads to a gradual photoluminescence decrease due to the formation of the non-luminescent copper-based alloy in the QDs structure. Finally, the presence of glutathione initiates a ligand exchange process followed by some QDs surface treatment enhancing defect-related photoluminescence. As a result, three different kinds of sensor responses for three analytes allow claiming development of a new selective QD-based sensor suitable for biomedical applications.

Lanthanide coordination polymers functionalized by 5-nitroisophthalic acid: Synthesis, structure-DFT correlation and photoluminescent sensor of Cd2+ ion

Lanthanide coordination polymers (LnCPs) are influential chemosensors when designed to undergo a detectable change in optical properties upon interacting with target analytes. This work reports interaction of metal ions with LnCPs leading to elicit changes in fluorescence emission intensity, an essential step en route to developing sensitive and selective systems for metal-ion sensing. Towards this goal, solvothermal reaction of 5- Nitroisophthalic Acid (5-NIAH2) and Ln (NO3)3⋅xH2O produced seven Ln-coordination polymers {[Nd (5-NIA) (5-NIAH) (H2O)2]⋅CH3CN}n (1), {[Sm (5-NIA) (5-NIAH) (H2O)2]⋅CH3CN⋅H2O}n (2), {[Gd (5-NIA) (5-NIAH) (H2O)2]⋅(H2O)2}n (3), {[Tb (5-NIA) (5-NIAH) (H2O)2]⋅CH3CN)}n (4), [Dy (5-NIA) (5-NIAH) (H2O)2]n (5), [Ho(5-NIA) (5-NIAH) (H2O)2]n (6) and [Er2 (5-NIA)3(H2O)3(CH3CN)]n (7) with two-dimensional structures. The as-synthesized polymers are characterized by powder X-ray crystallography, infrared spectroscopy, thermogravimetric analysis, photoluminescence and DFT studies. The luminescence properties of [Tb (5-NIA) (5-NIAH) (H2O)2]⋅CH3CN)}n (4) is investigated. The CP-4 is highly sensitive for the detection of Cd2+ exhibiting most intensive fluorescence quenching with the lowest limit of detection. Other metal ions, including Co2+, Fe3+, Fe2+ and Pb2+ are also detected demonstrating the range of sensing capabilities.

Maize starch derived boron doped carbon spheres via facile solvothermal route as the photoluminescence sensor for determination of pH and Cr(VI)

In this work, a kind of boron doped carbon spheres (B-CSs) was successfully synthesized utilizing maize starch as carbon source and boric acid as dopant via facile solvothermal method. The chemical structure of the prepared B-CSs was systemically investigated by TEM, FT-IR, XRD, XPS and EDS. The synthesized B-CSs feature spherical structure with average size of ∼254 nm and exhibit strong photoluminescence (PL) with maximum emission at a wavelength of ∼453 nm under irradiation at 350 nm, leading to a quantum yield of 6.2%. Furthermore, the aqueous pH and Cr(VI) has a significantly various impact on the PL intensity of B-CSs, which can be flexibly utilized as the PL sensor for detection aqueous pH and Cr(VI) in aqueous. Particularly, the B-CSs have a desirable sensitivity and selectivity for detection of Cr(VI) with a low detection limit of ∼0.34 μmol l−1. Conclusively, our work provides a novel and dual-functional fluorescent sensor for detection of the pH and toxic metal ions in water environment.

A Benzothiadiazole-Based Eu3+ Metal-Organic Framework as the Turn-On Luminescent Sensor toward Al3+ and Ga3+ with Potential Bioimaging Application.

The design and preparation of novel multifunctional lanthanide metal-organic frameworks (Ln-MOFs) have been arisen widespread attention. In particular, Ln-MOFs have shown great luminescence potential in chemical sensing. Herein, a new benzothiadiazole-based Eu-MOF {[(CH3)2NH2][Eu(BTDB)2]·2H2O}n (JXUST-11) was obtained based on 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid (H2BTDB), which exhibits a chain-based three-dimensional framework. Moreover, JXUST-11 is considered as a photoluminescent sensor to identify Al3+ and Ga3+ ions by fluorescence enhancement with the detection limits of 2.9 and 10.2 ppm, severally. Importantly, Al3+ and Ga3+ can be discerned with the naked eye by color change under a natural lamp. In addition, a portable MOF film based on JXUST-11 was developed for Al3+ and Ga3+ detection. This is the first Ln-MOF that can be employed as a naked-eye fluorescent probe to identify Ga3+. Interestingly, JXUST-11 is also capable of detecting Al3+ and Ga3+ in living cells.

Dynamic synthesis of CdTe NRs: Diameter dependent tuning of PL quenching efficiency for sensitive organic vapor detection

Cadmium telluride (CdTe) is one of the well-explored semiconductors in the history of material science research, because of its innumerable benefits in all dimensional nanostructures. However, no endeavor has been dedicated as of now to understanding the size-dependent tuning of nonradiative emission efficiency and how it influences the sensitive detection of organic vapors (ethanol and acetone) through photoluminescence (PL) quenching mechanism. Herein, the aspect ratio of CdTe nanorods (NRs) is varied by changing its diameter while keeping the axial length constant through electrodeposition into lab made anodic aluminium oxide (AAO) membranes. The growth kinetics and thermodynamics involved while electrodeposition of CdTe NR in each distinct pore diameter of AAO membrane is studied and reasoned. The surface morphology of variable diameter AAO membranes and NRs, respectively fabricated under various electrochemical parameters are observed through a field emission scanning electron microscope. The relation between NRs dimension and structural parameters like d-spacing, crystallite size, band area ratio, and exciton-phonon ratio are extracted from X-ray diffraction and Resonance Raman spectroscopy. The strongly luminescent CdTe NRs, coupled with their chemical durability and organic molecule affinity displayed a sensitive response of ~12 and 6 ppm to ethanol and acetone vapors in the range of 10–100 ppm as a PL sensor. The carrier lifetime measurement through time-correlated single photon counting spectroscopy endorses the role of increased recombination density with a decrease in the diameter of NRs.

Synthesis of ZrO2:Dy3+ Nanoparticles: Photoluminescent, Photocatalytic, and Electrochemical Sensor Studies

Solution combustion was employed to create a series of ZrO2:Dy3+ (1-11 mol percent) nanoparticles (NPs) using oxalyl dihydrazide (ODH) as the fuel. ZrO2:Dy3+ NPs were subjected to calcination at about 700°C. ZrO2:Dy3+ NPs comprised of 1 to 11 mol% of Dy3+ were characterized by employing the X-ray diffraction (XRD), transmission electron microscopic (TEM), UV-visible, and X-ray photoelectron spectroscopic (XPS) techniques. The crystallite diameters of 1 to 11 mol% ZrO2:Dy3+ NPs were observed to range from 8.1 nm to 16.3 nm, exhibiting spherical shape. According to BET tests, the pore volume of ZrO2:Dy3+ NPs was determined to be 100.129 cm3/g. The mean pore diameter of ZrO2:Dy3+ NPs was determined to be 4.803 nm from the Barrett-Joyner-Halenda (BJH) plot. The photoluminescence and photocatalytic dye degradation properties of ZrO2:Dy3+ NPs were investigated. The acid red 88 (AR88) dye was applied to appraise the photocatalytic activities of the NPs under UV irradiation. ZrO2:Dy3+ NPs with 3 mol% Dy3+ exhibited improvised photocatalytic activity due to the operative departure of charge carriers. The electrochemical examination of ZrO2:Dy3+ NP modified carbon paste electrode in 0.1 N HCl demonstrated considerable redox potential output, as evidenced by cyclic voltammetric and amperometric measurements. The electrochemical sensor studies on ZrO2:Dy3+ NPs exhibited potentiality towards sensing of highly toxic metals like mercury and lead.

A Sensitive Photoluminescent Sensor Based on Highly Charged Monoruthenium(Ii) Complexes for Dopamine Detection

A Sensitive Photoluminescent Sensor Based on Highly Charged Monoruthenium(Ii) Complexes for Dopamine Detection

Multiple heteroatom-doped photoluminescent carbon dots for ratiometric detection of Hg2+ ions in cell imaging and environmental applications.

Photoluminescence detection and imaging of Hg2+ ions in the biochemical living system are of great importance. In this study, a new photoluminescent probe based on nitrogen (N), sulfur (S), and boron (B) multiple heteroatom co-doped carbon dots (NSB-CDs) is synthesized for the ratiometric detection of Hg2+ ions. The prepared NSB-CDs possess good aqueous solubility, excellent pH and ionic stability, excitation dependency, and high quantum yield (QY = 17.6%). The ratiometric photoluminescent sensor NSB-CDs exhibit high selectivity, sensitivity, and interference towards Hg2+ ions over other metal ions. After adding Hg2+ ions, the emission intensity of the NSB-CDs exhibits a large redshift from 452 to 496 nm (up to 44 nm), corresponding to a notable change from blue to green emission in aqueous solutions. The association constant (Ka), the limit of detection (LOD), and the limit of quantification (LOQ) for NSB-CDs/Hg2+ complex are calculated to be 3.6 × 104 M-1, 3.1 × 10-9 M, and 10.4 × 10-9 M, respectively, in the range of 0-30 × 10-6 M. The live cell bioimaging of HCT-116 cells with NSB-CDs validates the application of multicolor imaging for the detection of Hg2+ ions in aqueous media and biological systems. Moreover, the potential use of the NSB-CDs/Hg2+ complex for real sample analysis is demonstrated.

Amino-Functionalized Ti3C2 MXene Quantum Dots as Photoluminescent Sensors for Diagnosing Histidine in Human Serum

Amino-Functionalized Ti₃C₂ MXene Quantum Dots as Photoluminescent Sensors for Diagnosing Histidine in Human Serum

An “on-off” ratio photoluminescence sensor based on catalytically induced PET effect by Fe3O4 NPs for the determination of coumarin

Herein, using Fe3O4 nanoparticles (Fe3O4 NPs) as a magnetic artificial peroxidase, an “on–off” ratiometric photoluminescence sensor with high-sensitivity and high-selectivity for coumarin was constructed based on photoinduced electron transfer (PET) between 7-hydroxycoumarin and rhodamine B (RB). The results showed that Fe3O4 NPs catalyzed H2O2 to generate nucleophilic group ·OH, which attacked the active site of coumarin and produced strong fluorescent 7-hydroxycoumarin molecules. Then, the fluorescence of RB was quenched with 7-hydroxycoumarin through the PET effect. The ratio signal generated in the above process was used for the quantitative detection of coumarin. Under optimized conditions, the linear range 0.5–25 mg/L was acquired for coumarin with the detection limit of 0.016 mg/L. This method had excellent selectivity and the recovery rate was 81.8%−106.8% with the relative standard deviation less than 5.6%, so it can be used for the quantitative analysis of coumarin in complex matrix samples.

Synthesis of PANI@ZnO Hybrid Material and Evaluations in Adsorption of Congo Red and Methylene Blue Dyes: Structural Characterization and Adsorption Performance

In this research, a simple oxidation chemical process was applied for the synthesis of novel PANI@ZnO nanocomposite. The prepared nanocomposites were characterized by XPS, XRD, FTIR, SEM, TGA and N2 adsorption–desorption isotherms. Thereby, PANI@ZnO highest SBET values (about 40.84 m2 g−1), total mesoporous volume (about 3.214 cm3 g−1) and average pore size (about 46.12 nm). Afterwards, the prepared nanomaterial was applied as novel nanoadsorbent for the adsorption of Congo Red and Methylene Blue dyes from aqueous solutions at 298 K and pH 5.0. Besides, the pseudo-second-order model was obtained the best for the adsorption of both dyes. In the case of isotherm models, the Freundlich model showed the best fit. After removal, the spent adsorbent was regenerated. With the regeneration repeated five cycles, the PANI@ZnO regeneration efficiency remained at a very adequate level. These results are heartening in respect with the objective to utilize them in the field of sensors technology and research related to the photoluminescence sensor application.

Humidity-sensitive CsPbBr3 perovskite based photoluminescent sensor for detecting Water content in herbal medicines

Excessive water in herbal medicines (HMs) can cause pests infestation, mildew, and decomposition of active ingredients during storage. The classical detection methods for water content are still unsatisfactory due to the requirement of sophisticated manipulation, long time consumption and usage of large amounts of toxic toluene. Herein, hot injection method was adopted to synthesize humidity-sensitive CsPbBr3 perovskite, which was used to develop a novel photoluminescent (PL) sensor on a paper substrate for rapid detection of water content in HMs with a turn-off mode. Due to the strong ionic nature of CsPbBr3 and the high aqueous solubility of CsBr, CsPbBr3 perovskite is very unstable upon the exposure of water. The signal off can be attributed to the phase change from luminescent CsPbBr3 to non-luminescent CsPb2Br5 according to the results of XRD pattern analysis of CsPbBr3 perovskite before and after water exposure. The PL intensity of CsPbBr3 is linearly related to the water content within the range of 1–17 %. For Seutellaria baicalensis and Astragalus flavone, the detection limits are 0.75 % and 0.67 %, respectively. The results of recovery tests for the two HMs are within the range of 96.7–102.5 %. This work realizes the application of CsPbBr3 perovskite in the field of pharmaceutical analysis, and shows the application potential for the control of water content in other types of samples sensitive to humidity.

A compact optical sensor for explosive detection based on NIR luminescent quantum dots

Detection of explosive traces in the vapor phase is of primary importance for safety and security in several environments. Different detection methods with high sensitivity are available in the market, but they are typically expensive and require specialized personnel to be operated. Here, we propose a compact, low-cost sensor for explosive detection based on the photoluminescence (PL) quenching of solid-state PbS quantum dot solids cast from the solution phase on a silicon substrate. We demonstrate the sensor capability to detect nitrobenzene vapor at a concentration as low as 445 ppb in air at room temperature, overcoming the performance of other state-of-the-art quantum dot-based PL sensors for nitroaromatic compounds. Moreover, the proposed system can be realized with off-the-shelf electronics and does not need any additional laboratory equipment to be operated, thus paving the way for its deployment in distributed sensor networks.

High-efficiency energy transfer pathways between Er(III) and Tm(III) in metal-organic frameworks for tunable upconversion emission and optical temperature sensing

In this work, Er3+/Tm3+ co-doped lanthanide metal-organic frameworks with uniform rod-like shape were obtained by one-step method, maintaining porous structure as well as upconversion characteristics under near-infrared excitation. The significant enhancement in upconversion emissions of Er3+ have been observed due to the Tm3+-mediated energy transfer pathways. By modulating the ratio of Er3+ to Tm3+, tuning upconversion luminescence from yellow to blue light were achieved. Efficient energy transfer from Er3+ to Tm3+ were demonstrated in metal-organic frameworks and the mechanism was discussed in detail. In addition, the Er/Tm-MOF was applied as an optical thermometer based on thermally coupled levels of Er3+, exhibiting high absolute and relative sensitivities. These results will pave an avenue to novel Ln-MOFs for color-tunable photoluminescence and optical sensors.

Post-modification preparation of dual-emission Eu3+@ZnII MOFs-based hybrid material and its application in highly sensitive ratiometric sensing for asthma wonder drug-procaterol enhanced by HCO3- and temperature

Currently, procaterol has been widely used as an asthma wonder drug; however, the overuse of procaterol easily leads to arrhythmia, and tachycardia decreased blood pressure. Metal organic frameworks (MOFs) are a new class of hybrid porous materials that have attracted great attention in the past 20 years. These metal-organic framework composites have highly efficient host-guest interactions and are excellent fluorescent sensing materials. In this work, an effective detection method to control the amount of procaterol was designed. A unique three-dimensional (3D) cluster-based metal-organic framework (MOF), namely [Zn2L(DEF)3]n (Zn-MOF, H4L=[1,1′:4′,1′'-terphenyl]- 3,3′',5,5′'-tetracarboxylic acid) can be prepared through the solvothermal method. Furthermore, through postsynthesis strategies, Eu3+ is loaded into cluster-based Zn-MOF to form dual-emission Eu3+@Zn-MOF, which can be employed as a ratiometric photoluminescent sensor for detecting the amount of wonder drug procaterol with a high K sensing constant value (6.12 ☓ 105 [M−1]) and a low limit of detection (LOD) value (46.10 nM). In addition, HCO3- can be effectively detected with a low LOD value (8.28 nM) in procaterol solution while other anions do not respond, which also reveals the pharmacological effects between HCO3- and procaterol. Furthermore, in the HCO3- solution, Eu3+@Zn-MOF exhibits a more sensitive sensing performance for the procaterol with high sensitivity and excellent recovery. On the other hand, Eu3+@Zn-MOF is a highly sensitive ratiometric temperature sensor in the range of 298−353 K. The detection sensitivity of Eu3+@Zn-MOF towards procaterol under the different physicochemical temperatures of the human body (303 K, 308 K, and 313 K) is also compared, This comparision indicates that temperature of 303 K has an enhanced sensing performance for procaterol in comparison with other detection temperatures. In conclusion, with the help of HCO3- and a suitable temperature (303 K), the detection sensitivity of Eu3+@Zn-MOF towards procaterol can be significantly improved and enhanced.